The present disclosure relates to an intake and exhaust device for an automotive engine.
As an example of an intake and exhaust device for an automotive engine, Japanese Unexamined Patent Publication No. 2016-217249 discloses an intake device for a supercharged engine. The intake and exhaust device includes: an engine body; an intake passage having a downstream end connected to the engine body via an intake manifold; an exhaust passage having an upstream end connected to the engine body via an exhaust manifold; and an exhaust gas recirculation (EGR) passage branching off from the exhaust passage and having a downstream end connected to the intake passage.
Furthermore, the intake passage cited in the Japanese Unexamined Patent Publication No. 2016-217249 includes a supercharger compressor interposed in the intake passage, and the supercharged engine further includes: a second intake passage (an air bypass passage) branching off from this intake passage upstream of the compressor, and connected downstream of the compressor; and a flow rate adjustment valve (an air bypass valve) changing a cross-sectional flow area of the second intake passage. The EGR passage has an upstream end connected upstream of a portion where the second intake passage branches off from the intake passage.
When such a supercharged engine runs, external EGR gas taken out of the exhaust passage is introduced into the intake passage upstream of the branching portion.
As cited in Japanese Unexamined Patent Publication No. 2016-217249, when the external EGR gas is introduced into the intake passage, such substances as water and soot contained in the external EGR gas are also sent back to the intake passage.
Usually, the substances contained in the external EGR gas are guided to a combustion chamber with a flow of the gas, and treated by evaporation and combustion in the combustion chamber. In order not to leave the substances in the intake passage, such substances are required to be smoothly introduced into the combustion chamber.
In view of the above requirement, the present disclosure is directed to an intake and exhaust device for an automotive engine. The device includes a second intake passage apart from an intake passage, allowing a substance in external EGR gas to smoothly lead to a combustion chamber.